it happens once every four years. the countdown to inauguration is on. >> when president obama takes the oath of office on monday, the inaugural celebration will be nothing compared to what it was back in 2009 when he was sworn in. abc's david kerley is in washington with more. good morning, david. >> reporter: bianna and dan, this is my third one. it gets cold every time the president gets ready to take the oath. while the weather is going to be the same, this is going to be a much different celebration than the one four years ago. ♪ the barricades are up. the viewing stands, built. the finishing touches going on floats. members of the military have already practiced parading. >> i -- >> reporter: and he's ready to take the oath a second time. ♪ at last >> reporter: beyonce and james taylor will perform. but this will be a very different affair. four years ago, 1.8 million people filled the mall. less than half that number, just 800,000, are expected this year. four years ago, nearly every one of the 29,000 hotel